Use of hypergolic propellants to power rockets and other space and/or aircraft is relatively common within the industry. Such propellants typically consist of a fuel (e.g., hydrazine) and an oxidizer which spontaneously ignite when they come into contact with each other. One advantage of hypergolic fuel systems are that ignition systems are not required or used for ignition and combustion of hypergolic propellants. Hypergolic fuel systems, however, can be extremely toxic and corrosive both to the propulsion system and to the environment. For this reason, the space industry is moving towards use of “green” propellants that will enable safer, more cost-effective space flight. “Green propellants” or “green fuels” are not hypergolic or toxic and offer a higher return on investment in not requiring ground support equipment and significant time for delivery and filling of fuel within the propulsion system.
The benefits of using “green” fuels within propulsion and other mechanical systems are significant in that they offer higher energy output per weight and improved ignition reliability when paired with a compatible spark exciter unit. Consequently, “green” fuels also require less storage space than that which is required for other conventional fuels.
Relative to the standard hypergolic fuels such as hydrazine, these “green” fuel mixtures are more difficult to ignite reliably and require much more energy to ignite and to burn. What is therefore needed within the industry is an improved spark exciter system which is capable of consistently initiating combustion of various types of “green” fuels.
NASA Glenn Research Center has published the results of a test of several potential spark exciter systems, and established that a spark exciter system that is capable of reliably igniting and sustaining combustion of a “green” fuel mixture of liquid oxygen and liquid methane (LO2/LCH4) requires approximately 200-300 sparks per second, each with 55-75 mJ of energy delivered per spark, a breakdown voltage on the order of 9-10 kV, and a deterministic and repeatable time to first spark. However, current commercially available spark exciters have not been able to consistently achieve ignition with sufficient reliability for aerospace applications.
The present disclosure provides a spark exciter system capable of reliably igniting non-hypergolic and “green” fuels in aerospace applications. Such applications may include various components of aerospace propulsion systems such as “green fuel” rocket emission systems, thruster systems, etc. Other applications for the spark exciter system include, but are not limited to, flight systems such as aircraft engines, race cars and other landcraft engines, systems used within the oil and gas industry, power turbines, watercraft engines, etc.